Influence of selected design variables on thermo-mechanical stress distributions in plated-through-hole structures

The finite element method (FEM) is used to study the stress concentration in plated-through-hole (PTH) structures of multilayered printed circuit boards (MLB). The research gives new data on how surface shape and mechanical properties affect the design of MLBs. Three-dimensional and axisymmetric FEM models are developed to analyze the stresses in FR-4 and kevlar-polyimide MLBs. Results show that stresses decrease with an increase in plate thickness and spacing. Stress relief is provided by innerplanes, internal pads and signal layers in FR-4 MLBs. Stresses increase along the length of the barrel for Kevlar-polyimide MLBs.